Portable building



FIG. 1 is a plan view of the portable building showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a side view of a first side thereof;

FIG. 5 is a side view of a second side thereof; and,

FIG. 6 is a frontal perspective view thereof. 

The ornamental design for the portable building, as shown and described. 